Using corrugated tubes in external molten salt receivers

Abstract

CFD models have been used to show the potential of using corrugated tubes instead of smooth tubes at a solar thermal receiver using molten salt as heat transfer fluid. The results were compared on the basis of a 700 MWth receiver. Absorber tubes with an inner diameter between 32.8mm and 70 mm using a helical ribbed structure have been analyzed. The results show that a positive effect can only be achieved for configurations where the fluid velocity is lower than for the base hydraulic design with a fully developed turbulent flow. The presented approach proposes therefore tubes with larger inner diameter and reduced fluid velocity and pressure drop. The difference in pressure drop to the base design can then be used to introduce a swirl flow which leads to better mixing of the fluid and therefore lowers the temperatures of the tube wall, the fluid and also the thermal gradients. Corrugated tubes can be used to add an additional design parameter for a thermo-hydraulic optimization of the receiver.CFD models have been used to show the potential of using corrugated tubes instead of smooth tubes at a solar thermal receiver using molten salt as heat transfer fluid. The results were compared on the basis of a 700 MWth receiver. Absorber tubes with an inner diameter between 32.8mm and 70 mm using a helical ribbed structure have been analyzed. The results show that a positive effect can only be achieved for configurations where the fluid velocity is lower than for the base hydraulic design with a fully developed turbulent flow. The presented approach proposes therefore tubes with larger inner diameter and reduced fluid velocity and pressure drop. The difference in pressure drop to the base design can then be used to introduce a swirl flow which leads to better mixing of the fluid and therefore lowers the temperatures of the tube wall, the fluid and also the thermal gradients. Corrugated tubes can be used to add an additional design parameter for a thermo-hydraulic optimization of the receiver.